1. Field of the Invention
This invention relates to a method for determining the temperature of a molten metal bath in a top blown oxygen converter and more particularly to a method for determining the temperature of a molten metal bath after the conversion process has progressed a predetermined period of time and thereafter determining the further increases in the temperature of the molten metal bath as the conversion process progresses to completion.
2. Description of the Prior Art
It is highly desirable in metal conversion processes, especially in top blown oxygen converters, to determine the temperature of the molten metal bath as the conversion process progresses and to predict, prior to turndown, the temperature of the molten metal bath at the completion of the conversion process. It is also highly desirable to predict and control the formation of FeO in the slag which rapidly increases during the latter stages of the conversion process.
Several proposals have been made in the past for determining the temperature of a molten metal bath in a top blown oxygen converter. For example, in U.S. Pat. No. 3,377,158, a bomb thermocouple is dropped into the molten metal bath after the conversion process has progressed for a preselected period of time. The thermocouple measures the temperature of the molten metal bath at the time of the conversion process when it is dropped into the molten metal bath and is used as the initial measured temperature for subsequent temperature determinations. The final temperature of the molten metal bath at the end of the conversion process is determined by adding to the initial measured temperature of the bath, the temperature increase attributable to the oxygen consumed in the conversion process. The accuracy of the calculated temperature at turndown is dependent on the accuracy of the initial measured temperature by the thermocouple.
It is well known that there is a temperature gradient within molten metal bath with the highest temperature in the jet oxygen-hot metal reaction zone. It is also feasible that the slag formed during the conversion process is at a differential temperature to that of the molten metal. These factors affect the accuracy of determining an accurate initial measured temperature and therefore, also affect the accuracy of the calculated temperature at turndown.
Another proposed procedure for determining the temperature of the bath is disclosed in U.S. Pat. No. 3,489,518, granted on Jan. 13, 1970, and entitled "Carbon Determination Method And Apparatus". In this process, the amount of carbon in the charge material is first determined and the other constituents of the charge are also conventionally sampled and analyzed for heat release determination. The increase in the temperature of the molten metal bath attributable to the oxidation of the metalloids is determined by calculating the heat of formation of each of the metalloids and the heat of formation of the gaseous carbon compounds. One of the inherent deficiencies in this method is the necessity of accurately sampling prior to analyzing the charge for the metalloid constituents. An error in the sampling or analysis of one of the metalloids results in a temperature error equivalent to the error in the weight of metalloid multiplied by the heat of formation of the particular metalloid.